Pump and accumulator unloader assembly



y 1961 J. E. THRAP PUMP AND ACCUMULATOR UNLOADER ASSEMBLY zsheets-sheei 1 Filed Dec. 26, 1956 hazziar' .JDHN ETHRHP May 2, 1961 J. E. THRAP 2,982,217

PUMP AND ACCUMULATOR UNLOADER ASSEMBLY Filed Dec. 26, 1956 2 Sheets-Sheet 2 Lzazzfav 5i w mgaw $723k Unit d t e a en -Q7" PUMP AND ACCUMULATOR UNLOADER ASSEMBLY .lohn Thrap, East Cleveland, Ohio, assignor to Thompson Ramo Wooldridge Inc., a corporation of Ohio Filed Dec. 26, 1956, Ser. No. 630,606

6 Claims. (Cl. 103-42) surized fluid are used the demand is intermittent but a continuous supply of power is available for operating the putnp. The pressurized fluid is therefore usually pumped into an accumulator wherein the fluid is maintained at a pressure to be drawn therefrom upon demand. This provides a supply of fluid when the pump is running at slower speeds and provides a supply which can be drawn on when all of the fluid consuming devices are in use. However, at higher engine speeds which operate the pump more rapidly and on occasions when little fluid is consumed from the accumulator, means must be provided to prevent an excessive pressure from beingdeveloped in the accumulator. The present invention contemplates the provision of a pump and control system wherein an ample supply of pressurized fluid is supplied to an accumulato'r and wherein excessive pressures are prevented from developing in the accumulator while the accumulator supply and pressure is maintained.

It is accordingly an object of the present invention to provide an improved compact pump and control system for continuous operation and supplying a continuous flow of the pressurized fluid to an accumulator and to auto matically interrupt the flow to the accumulator when a pre-determined back pressure is reached.

Another object of the invention is to provide an improved pump and flow control system wherein damage to the system and to the accumulator are prevented by automatically by-passing the fluid from the pump at a predetermined accumulator pressure.

A further object of the invention is to provide an improved and reliable control valve system for automatically by-passing fluid from the pump at a predetermined delivered pressure. p

A still further object "of the invention is to provide an automatic valve control system which is safe in operation and which will operate to automatically relieve fluid pressure despite the unforeseen failure of certain elements of the system.

Another object of the invention is to provide an improved pump and control system wherein the delivery pressure of the pump is automatically relieved at a pre- 2,982,217 Ratented lVlay Z, 1961 determined output of pressure and wherein the pump is automatically incapacitated at said predetermined pressure.

A further object of the invention is to provide an improved pump fiow control system which is compactly housed in a single unit with the elements operating cooperatively within the unit and requiring a minimum of housing space.

Other objects and advantages will become more apparent from the detailed disclosure of the principles of the invention in connection with the description of the preferred embodiment in the specification, claims and drawings in which:

. Figure 1 is a vertical sectional view taken through the housing and illustrating the constructional details of the pump and the relief valve;

Figure 2 is an end elevational view illustrating-th housing; and,

Figure 3 is a side elevational view of the housing with parts broken away to show the interior construction and being enlarged in comparison with Figure l.

While the elements of structure are in connection with the pressure pump and control system for delivering'a fluid to an accumulator, in the preferred embodiment, it will be understood that the various features and structural elements maybe utilized in other environments taking advantage of their natural advantages, although they find particular utility in the preferred form disclosed.

In the drawings:

The operating elements of the pump and control system are shown enclosed in a housing 4 which incorporatesa main casting 6 with an element supporting casting 8 attached thereto such as by bolts 10. Studs 12 may be provided to attach the entire housing in its operative location'such as on the head of an automobile or'the like. The main casting 6 carries the cap or shell 14 which is telescoped over the casting and sealed thereto such as by an O-ring gasket 16. This cap forms a hollow chamber which provides a reservoir 18 for the fluid. The fluid is drawn from this reservoir for pumping through the hydraulic circuit of which the pump is a part, including the accumulator, and is returned to the reservoir when the control valve system senses an excessive pressure in the delivery conduit.

Operating fluid is returned to the reservoir 18 through a fitting 20 in the cap 14 connected to the hydraulic circuit served by the pump. The fitting discharges into the reservoir 18 within a filter chamber 22in the interior of a cylindrical filter 24.- The filter is held in place by a plate 26 which seals the outer open end and the inner end of the filter 24 is held against the inner surface of the cap 14 by a spring disk 28 held in place by a pin 30, which is secured in a member 32 welded or otherwise connected to the inside of the cap 14. The fluid passes from the chamber 22 within the filter 24 into the reservoir 18. The reservoir 18 may be provided with additional chamber capacity by an expansion portion shown at 34 in Figure 2, but omitted from Figures 1 and 3 for clarity.

The fluid is drawn from the reservoir 18 and delivered under pressure by the pump 36. The pump is driven by a shaft 38 which carries at its outer end, a pulley 40 shown as adapted to receive a V-belt but which maybe driven by other suitable means. The shaft 38 is carried in the casting 6 by ball bearings 42 and is provided with a seal 44. Additional bearings and seal members such as 46 may be provided and the inner end of the shaft 38 connects such as by a spline 47 to the cylindrical rotor or pump element 48. Pump element 48 drives pump element 50 in a manner that will be described and these cylindrical pump elements 48 and 50 are rotatably carried on angularly. disposed intersecting axes in communicating cylindrical chambers --52 and 54. The cylindrical chamber 52 terminates in a flat end wall 56 and the other chamber 54 terminates in a flat end wall 58, which is the interior surface of a plate 60, held on the open end of the casting 8 by bolts 62, thereby forming sealing and porting surfaces.

. The cylindrical pump elements 48 and 50 carry annularly arranged radially disposed cylindrical bore openings such as'64 and 66 in which slide pumping sleeves 68 and 70 having angular legs or arms. It will be observed that the lower cylindrical pump element 50 is tied to the upper pump element 48 by the series of pump sleeves and that as the upper pump element is rotated, the lower element 50 is also driven in rotation. The sleeves have a hollow interior to intercommunicate expanding and con tracting pump chambers such as 72 shown at opposite ends of the sleeves 68 in the rotors. It will be observed that as the pump rotates each of the chambers will gradually expand through 180 of rotation of the pump and will contract during the remaining 180. During the expansion period of the chamber 72 for example, it is in communication with an intake chamber 74 which is fed fluid through an intake opening 76. During the discharge or contraction period of the chamber 72, it will be in communication with the delivery conduit 73 which receives the: fluid pumped through a small passageway 80. The pump elements 48 and 50 are initially held against the fiat ends 56 and 58 of the chambers by a spring biased hollow sliding plunger 82 which slides in a cylindrical bore 84 in the lower pump element 50. A spring 86, bottoms in the bore and extends upwardly within the plunger 82 to urge it outwardly against the hub 88 on the opposite pump element 48.

The primary source of force however, to urge the pump elements 48 and 50 into operative engagement with the end walls 56 and 53, is the pressure control chamber 88 between the pump elements. In operation pump generated pressure at approximately one-half of the delivery pressure of the pump is supplied to the pressure control chamber 88 through the normal running clearances of the movable pump components, thereby to maintain a proper seal at the porting and sealing surfaces. A venting passageway is provided to vent the chamber 88 through the passageway 90 to a control function as will later be described in detail.

The relief valve is shown generally at 91. The valve is housed in a cylindrical hole 92 bored in the casting 8. In the cylindrical hole is positioned a valve insert sleeve 94. Within the sleeve slides the valve operating plunger or piston 96.

The position of the valve 96 is derived from the pres sures acting thereon supplied by the coil compression spring 98, the fluid pressure in the delivery conduit 78 which acts on the flat end 100 of the valve, and the pres sure in chamber 102 which acts on the flat surfaces of the opposing end 104 of the valve.

The pressure on end 104 in chamber 102 is supplied through a control passageway 106 as shown in both Figures l and 3. The pressure in this control passageway is regulated by pilot valve shown generally at 168 in Fig. 3,

and its operation will be described later in detail.

The chamber 102, of the pressure relief valve houses the coil compression spring 98 which is held in place by plug 110, the plug being threaded into the end of a tubular extension 112 which in turn is threaded into the cylindrical bore 92 in the casting 8.

Since the chamber 102 is connected to the pressure pilot valve.

in the delivery conduit 78, the combined fluid pressure with the force of the spring 98 on the end 104 of the valve plunger 96 will keep the valve plunger in the position shown in Figure l to keep the passageway to the pump closed, maintaining the pump in operating condition. The plunger 96 in this position will also keep the delivery conduit 78 closed by the close clearance between the relief valve plunger 96 and the sleeve 94 at the end of the valve plunger. The control passageway 106 connects to the delivery passageway '78 through the pressure passageway 114, shown in Figure 3. The delivery conduit 78 receives pressurized fluid from the pump and delivers the fluid through a check valve 116 and to a fitting 118 which is connected to suitable lines for delivering the fluid to an accumulator or the like. The pressure passageway 114 is tapped laterally into the delivery conduit through an orifice 120.

The control passageway 106 is connected either to the pressure passageway 114 or to the reservoir 18 through a vent passageway 122. This control is obtained through the pilot valve 108. The pilot valve comprises a sliding valve plunger 126 positioned within a sleeve valve liner 128 within the bore 130 in the housing member 8. The end of the bore is closed by plug 132 having a pair of annular flanges 135 which carry between them an O-ring seal 136. The plug 132 supports a coil compression spring 134 which engages the sliding valve plunger 126. The spring is positioned in the chamber 138 and the valve will move into this chamber to connect the control passageway 106 to the vent passageway 122.

. In the position shown in Figure 3, the two-way valve 108 connects the control passageway 106 to the pressure passageway 114 by means of its hollow interior 140 and a laterally bored hole 142 in the valve plunger 126. When the valve plunger slides to the right, as shown in Figure 3, the lateral bore 142 will be covered by the sleeve liner 128 and the laterally bored hole 144 will become aligned with the vent passageway 122 thus permitting the pressurized fluid in the control passageway 106 to flow through the center 140 of the hollow valve body and pass out through the bore hole 144 and through the vent passageway 122 into the reservoir 18. This, of course, vents the chamber 102 behind the relief valve plunger 96 and the delivery conduit presure 78, acting against the face 100 of the valve, will move it to the right as shown in Figure 2.

Although suflicient communication through the valve plunger 126 is achieved by the use of the lateral holes 142 and 144 alone to insure communication even with rotation of the valve plunger, annular grooves 143 and 145 are formed around the plunger for the respective bored holes.

The pilot valve plunger 126 is controlled by the pressure delivery conduit 78. At normal operating pressures, the pilot valve spring 134 has sufficient strength to hold the pilot valve in the position shown in Figure 3, wherein the control passageway 106 is connected to the delivery conduit 78. When the pressure reaches a predetermined level, however, a control valve in the form of a ball valve 146, which is contained in the relief valve plunger, will open. This ball valve is held against the shoulder of a tubular opening 148 extending through the plug 150 which is threaded into the rear end of the relief valve plunger 96. The ball valve is normally held in seated position by coil compression spring 152 in the valve chamber 156 within the relief valve plunger 96. An excessive pressure will unseat this valve 146, venting the chamber 102 behind the relief valve, and also permitting the escape of pressure through the control passageway 106 to reduce the pressure in the chamber 138 behind the pilot valve plunger 126. This will move the pilot valve to the right and will completely vent the control passage way 106 to the reservoir through the opening 144 in the The ball valve 146 in the relief valve permits the fluid to flow into its chamber 146 and escape aesazlr 7 through the lateral orifices 158 in" the reliefvalve body to flow into an annular groove 160 extending around the relief valve 96. The pressure then escapes through first and second relief orifices 162 and 164 which may be arranged in rows and extend through the valve liner sleeve 94. The orifices 162 and 164 in turn communicate with an annular groove 1-66 cut in the bored hole 92 housing the relief valve and the fluid then flows out through the escape opening 168 intothe reservoir 18. e I -With the pressure drop in the relief valve chamber 102, therelief valve plunger 96 moves tothe right as shown in Figure 1. The face 100 'of the-relief valve plunger clears the relief orifices 162 and permits the fluid in. the delivery conduit .68 to escape through the orifices and pass out through the opening 68 into the reservoir. The

accumulator is not permitted to empty however, as the check valve 116 will operate by the ball 170 seating against the shoulders of an orifice defining member 172. The

check ball 170 will normally allow the passage of fluid delivered by the pump by moving away from the orifice 174 and compressing the ball retaining spring 176.

In addition to venting the delivery conduit 78, the movement of the relief valve plunger positions the annular groove 160 over the orifices 164 and an orifice 178 which extends through the sleeve 94 to communicate with thepump by venting passageway 90. Thus the fluid pressure in the-pressure control chamber 88 of'the pump is relieved by flowing through the passageway 90, through the orifice 178, through the groove 160, through the orifices 164, through the groove 166 and through relief orifice 1168. This will permit the pump rotors or pumping elements 48 and 50 to move away from the sealing and port- '=ing surfaces provided by the end walls 56 and 58 whereby Jthefluid will be directly by-passed between the inlet and outletportions of the porting surfaces;

--The foregoing conditions, which relieve the pressure in the delivery conduit 78 and which automaticallyr disable the pump 36, will continueuntilsuflicient fluid is used from the accumulator to drop the pressure therein .to a predetermined level.

At this level, the pilot valve spring 134 will be able to overcome the pressure acting on the end face 180 of the pilot valve, and the valve plunger 126 will again move to the leftto close off the vent passaegway 122 and connect the control passageway 106 to the pressure passageway 114. This will again direct cpressure up into the chamber 102 in back of the relief valve plunger 96 to return the relief valve to its closed position. This will again permit a build-up of pressure in the pump chamber 88 and with operation of the pump, pressure will return to the delivery conduit 78 to again pump fluid into the accumulator.

Although the operation of the pump and control system will be clear from the description of the individual elements and their structure and operative relationship to the other elements, a brief summary of the overall operation of the system will be helpful in understanding the advantages and objectives. The unit shown-at 4, is .driven by rotation of the shaft 38 through the pulley 40. .This rotates the pump 36 causing a build-up of pressure in the chamber 88 between the pump units 48 and 50 and causing'a fluid pressure to build up in the delivery con- .duit 78.- The fluid is discharged into an accumulator or .the like. 'During normal operation the pump will operate and fluid will be withdrawn from the accumulator as needed. If the discharge of the pump becomes larger than required by the accumulator due to the high speed of the pump or due to insuflicient demand fluid from the accumulator, an excessive pressure will buildup in .-the chamber 102 behind the relief valve plunger 96. Fluid is communicated to the chamber 102 through the ,pressure passageway 114, lateral hole 142 of the pilot valve plunger 126, the hollow center 140 of the pilot valve, the chamber 138 of the pilot valve, and the control passageway 106. At an excessive pressure in the relief :valve chamber 102, the ball valve 146 will open permitrelief passageway 168 to the reservoir 18. The relief valve plunger 96 will move to the right with the orifice 162 being exposed to the delivery conduit 78 to permitthe escape of fluid therefrom through the relief passageway 168. Fluid will be prevented from backing up from the accumulator by the ball valve 116. The pump .will automatically eflect internal by-passing by the groove 160 bridging the orifices 90 and ;164 to vent the pump chamber 88 and permit unloading of the elements 48 and 50, as explained previously.

The system will remain vented and disableduntil suflicient pressure is withdrawn from the accumulator to drop pressure in the pressure passageway 114 and permit the pilot valve spring 134 to overcome the pressure on the face 180 of pilot valve. This will break the communication between the control passageway and the reservoir through opening 144 and vent passageway 122, and will again place the control passageway 106 in communication with the pressure passageway 114 through the lateral opening 142 in the pilot valve. Pressure will then build up in the chamber 102 behind the relief valve plunger 96 and return the plunger to its closed position. A normal operation of the system will then continue until an excessive pressure is again reached in the accumulator.

Thus, it will be seen that I have provided an improved fluid control system which meets the objectives and advantages hereinbefore set forth. The system is rehable and will operate without the necessity of adjustment. The arrangement permits the operation of the pump at speeds which willvary over a wide range such as is encountered in power received from an automobile engine during driving operation. A suflicient fluid pressure will be maintained in the accumulator at all times and damage to the machine elements are avoided by the relief of the pressurein an automatic fashion at a predetermined pressure. v

I have, in the drawings and specification presented a detailed disclosure of the preferred embodiment of my invention, but it is to be understood that I do not intend to limit the invention to the specific form disclosed but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention. 7

I claim: v

1. A fluid pressure control system comprising a pump for delivering a supply of pressurized fluid, a delivery .conduit connected to the pump, a pressure relief valve lower pressure, pressure responsive means connected to the delivery conduit and to the valve pressure chamber and to the two-way valve operative to move the two-way V valve to the second position to vent the relief valve pressure chamber to move the relief valve member to open position responsive to drop in pressure in the pressure chamber with opening of said valve member, and means automatically operative to incapacitate the pump upon movement of the relief valve to open position.

2. A fluid pressure control system comprising a pressure pump including a pair of spaced cylindrical members angularly disposed within a cylindrical angular operating chamber flow ports in the ends of the chamber, an axially displaced pumping sleeve being knee-shaped and operating in cylindrical openings in the pumping memhers with a leakage of fluid into the space between the pumping members to create a pressure between said pumping members holding them in operative spaced positions against the ends of 'said' cylindrical chamber in operative communication with said flow ports, a pump disabling passageway leading to the space between said pumping members, a delivery conduitleading from the pump, a pressure relief valve connected to the delivery conduit and adapted to relieve the pressure of the conduit to prevent an excessive pressure from being delivered to an accumulator or the like, said pressure relief valve movable between an open and a closed position and operable in the open position to vent the passageway to the pump to relieve the pressure therein and effect a direct by-pass between the pump inlet and outlet, said pressure relief valve closing said pump disabling passageway in said closed position and opening said passageway to relieve the pressure between the cylindrical pump members and permit them to move away from the ends of the cylinder flow port to disable the pump, means defining a control chamber connected to said delivery conduit and exposed to said relief valve for holding it in closed position, a control valve connected to said control chamber and opening to vent the control chamber at a predetermined pressure, a first conduit connected to 'said delivery conduit, :1 second conduit connected to said control chamber, a third conduit open to a relief pressure, a two-way pilot valve connecting said first and second conduits in a first position and said first and third conduits in a second position, a first pressure responsive surface connected to said pilot valve and exposed to said control chamber to urge the pilot valve to first position, and a second pressure responsive surface connected to said pilot valve and open to said delivery conduit to urge the pilot valve to said second position, said pilot valve remaining in said first position until said control valve is open and said control chamber is vented.

3. A fluid pressure control system comprising a pressure pump for delivering a pressurized fluid to an accumulator or the like, a delivery conduit connected to the pump, a pressure relief valve connected to the delivery conduit and adapted to relieve the pressure of the conduit when operated to prevent an excessive pressure in the accumulator, said valve movable between open and closed positions, a control passageway leading to the relief valve to move it to one position when exposed to delivery fluid pressure and to move it to the other position when exposed to a reduced pressure, a pilot valve in the control passageway, said pilot valve connecting the control passageway to the delivery conduit in a first position and venting the control passageway in a second position, a surface on said pilot valve exposed to the pressure of said control passageway urging it to first position, biasing means urging the pilot valve to first position, means conmeeting the pilot valve to the delivery conduit whereby the pilot valve is moved from first position to the second position at a predetermined pressure in the delivery conduit when said biasing means is overcome, the venting of said control passageway in second position also relieving force on said surface of the pilot valve and means for relieving the pressure in said control passageway at a predetermined maximum pressure.

4. A fluid pressure control system comprising a pump for delivering a fluid under pressure to an accumulator or the like, a delivery conduit connected to receive fluid from the pump, a pressure relief valve connected to the delivery conduit and movable between a closed position and an open position where the delivery conduit is vented, a control chamber open to said pressure relief valve with fluid pressure holding said pressure relief valve in closed position, means connecting the control chamber to the delivery conduit so that the chamber pressure will be the same as the delivery conduit, means urging the relief valve toward open position during operation of the pump, a control valve connected to the controlchamber and being biased to closed position and having a pressure responsive surface exposed to the chamber to open the valve and vent the chamber at a predetermined maximum chamber pressure to cause the pressure relief valve to move to open position, and a pilot valve connected to the control chamber and movable between a first and a second position to close the chamber in first position and vent the chamber in second position and said pilot valve having means urging it toward second position during operation of the pump and having a pressure responsive surface exposed to said control chamber to hold the pilot valve in first position, said pilot valve moving to second position upon a pressure drop in said chamber due to the control valve moving into open position so that the control chamber is vented by both said control and pilot valves.

5. A fluid pressure control system comprising a pump for delivering fluid under pressure to an accumulator or the like, a delivery conduit connected to receive fluid from the pump, a pressure relief valve connected to the delivery conduit and movable between a closed position and an open position where the delivery conduit is vented, a control chamber connected to the delivery conduit and open to said pressure relief valve with fluid pressure in the chamber holding said pressure relief valve in closed position, means urging the relief valve toward open position during operation of the pump, a control valve connected to the control chamber and being biased to closed position and having a pressure responsive surface exposed to the chamber to open the valve and vent the chamber at a predetermined maximum chamber pressure to cause the pressure relief valve to move to open position, a pilot valve connected to the control chamber and movable between a first position to close the control chamber and a second position to vent the control chamber. a first pressure responsive surface connected to said pilot valve and exposed to said control chamber to hold the valve in first position and so that the valve will move to second position as the control valve opens, a second pressure responsive surface connected to the pi ot valve and open to said delivery conduit urging the pilot valve toward second position, and means urging the pilot valve to first position so that it will move to first position when the delivery conduit pressure drops to a predetermined value.

6. A fluid pressure control system comprising a pump for delivering fluid under pressure to an accumulator or the like, a delivery conduit connected to receive fluid from the pump. a pressure relief valve connected to the delivery conduit and movable between a closed position and an open position wherein the delivery conduit is vented, a control chamber open to said pressure relief valve with the fluid pressure in the chamber holding said pressure relief valve in closed position, means urging the relief valve to open position during operation of the pump, a control valve connected to the control chamber and being biased to closed position and having a pressure responsive surface exposed to the chamber to open the to move to open position, a pilot valve connected to said control chamber and to said delivery conduit and movable between a first and a second position, said pilot valve connecting said control chamber and said delivery conduit in saidfirst position, said pilot valve closing the delivery conduit to the control chamber at second position and venting the control chamber, a first pressure responsive surface exposed to said control chamber and connected to said pilot valve urging it to first position, a second pressure responsive surface connected to the pilot valve and open to said delivery conduit urging the pilot valve toward second position so that the pilot valve will move to said second position as the control valve opens and the control chamber pressure drops, and means biasing said pilot valve to first position so that it will move to first position when the delivery conduit pressure drops to a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS Stevenson July 7, 1953 Englesson Nov. 12, 1912 McAulay Sept. 15, 1914 Karnaseh Dec. 4, 1917 Schultz July 16, 1946 10 Schultz Aug. 24, 1948 Munroe Feb. 9, 1954 Barnes Nov. 22, 1955 Keel 'Aug. 21, 1956 Klessig et a1 Oct. 30, 1956 Pettibone et a1 Jan. 7, 1958 Pettibone May 20, 1958 Thrap et a1 June 17, 1958 Wysong et a1. Aug. 19, 1958 Klessig et a1 Apr. 7, 1959 

